Re: [Xen-devel] Questions about PVH in Xen 4.3 unstable

[tech mailinglists <mailinglists.tech@xxxxxxxxx>]

I thought that stubdoms for HVMs are great for security. Can it still be used for PV-on-HVM for security? Can only Linux run as PVH and Windows and so on still run as HVM?

2013/1/30 Samuel Thibault <samuel.thibault@xxxxxxxxxxxx>

tech mailinglists, le Wed 30 Jan 2013 11:33:23 +0100, a écrit :

> Actually I am running 4.2.1 with Linux 3.7.4 with Debian Squeeze as Dom0. For
> the HVM guests I am using ioemu stubdoms. When I understood PVH correctly it
> implements that what actually is done with PV drivers on HVM guests as a
> aggregated and seperate guest type.

It's more than that. The guest does not need ioemu at all.

> And does PVHs can get use of stubdoms?

And thus PVH have no use for stubdoms, since there is no ioemu to
execute in there.

> I am a little bit confused about a text I read that stubdoms are not needed for
> HVM guests which have PV drivers installed,

Ioemu is still needed for those domains, but running it in a stubdom
won't bring more performance, since what matters for performance will
not go through ioemu, when PV drivers are installed.

> is this correct or can a HVM guest always make use of stubdoms?

HVM can always make use of stubdoms to execute ioemu, but that won't
improve performance. It could improve early boot time, at best.

Samuel

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